Method of coating fiber containers



2 Sheets-S he t 1 INVENTOR Q Hans A. Eggzrss.

Dec. 28, 1943. H. A. EGGERSS METHOD OF COATING FIBER CONTAINERS FiledJan. 16, 1942 I P M ;TTORNEYS Dec. 28, 1943.

H. A. EGGERSS METHOD OF COATING-FIBER CONTAINERS 2 Sheets-Sheet 2 FiledJan. 16, 1942 INVENTOR Hons A. Eggerss M FM A71'ORNEYS Patented nee. 28,143

UNITED STATES PATENT OFFICE; f, i 2,337,981 p H I Mn'rnon or coa'rmo muncommas Hans A; Eggcrss, Van Wert, Ohio, assignor to Continental CanCompany, Inc.; New York, N. Y., a corporation of New York ApplicationJanuary 16, leiaseri i'no. 427,036 (01. 111-95) 6 Claims. I

My invention relates to a method of coating fiber containers. It hastodo, more particularly,

with a method for providing a protective thermoplastic resin coating onthe inside of fiber containers;

The cylindrical body of fiber containers which have wide commercial useis formed by convolutely or spirally winding heavy paper in overlappinglayers on a mandrel, the layers being glued or otherwise securedtogether. It has been customary to provide a protecting liner for acylindrical container t: this type. At present, one

method of fabricating a lined container is to pro vide an inner linersheet which has been precoated with a thermoplastic resin. Obviously,whether this liner paper is applied lap or butt scam, the edge of thepaper is exposed. It has been customary to seal this scam by'means oftape but usually this is the weakest point in the protecting seal of thecontainer since the method of joining this' tape to the coating makes itweaker than theoriginal ,film, whether adhesive is used on-the tape orwhether other methods are employed. Another method of producing aprotecting' film on] the interior of a fiber container consists incoating "the inside of-the completed drum with a solution containing asuitable resin and then evaporating the solvent. This method does resultin a coating over the seam of the liner paper, but entails all .theoperations necessary to remove the solvent from the drum, which normallyare difilcult operations, particularly if organic solvents are employed.Also in this latter-method of coating, it isdifficult to produce -anunbroken film since the exposed edge of the sheet acts like a wick andsoaks up the coating material rather than allowing it to be depositedon'the surface.

One ofthe objects of my invention is to pro vide amethod 6; applying afilm or coating on the interior of a fiber container after it has beenformed and in such a manner that there will be no seam in the protectivecoating. v

Another object of my invention is to provide a method of applyi g aprotective coating on the interior of a fiber container 1 that therewill be no danger of the coating peel- Another object of my inventionisto'provide a simple, effective and economical method for applyinga-coating of thermoplastic resin to the interior surface of a fibercontainer.

In its preferred form my invention contemplates applying a continuousfilm without seams in such a manner moplastic material into the materialof the container. In the case of a cylindrical container shell, thecalendaring rolls will operate inside and outsideof the shell and willsimultaneously produce relative rotation of the shell so that the entiresurface thereof will be covered with a continuous film.

. In the accompanying drawings, I have illustrated one form of apparatuswhich may be used in performing my method. In these figures, similarcharacters of reference designate correspond- I ing parts, and

l Figure lis an end view of the apparatus showing a cylindricalcontainer shell inposition. r Figure 2 is a front view of the apparatuswith the container shell broken awa for clarity.

Figure 3 is a p p n V ew, partly broken away, of the apparatus.

. Figure 4 is a vertical sectional view takenthrough the calenderlngrolls and illustrating how Ethey act. so

the shell showing the coatingapplied to thein- Figure 5 is a perspectiveview oi the apparatus. Figure 6 is a perspective view of a portion ofterior thereof. v

Figure '7 is a diagrammatic view illustrating the method where a mass ofthe thermoplastic material is employed.

' Figure 8 is a similar view showing how a sheet or stripof thethermoplastic resin may be employed.

With reference to the drawings, I have illustrated one form ofcalendering apparatus which may be employed with my process. However, itis to be understood that the form shownis merely one example and thatthe apparatus may take various forms.

The apparatus may constitute a base I having a cradle formed by rollers2' adapted to support the cylindrical container shell S. The base Isupports a standard 3 which supports on its upper end for rotation rollsl, .5 and 6.. The roll 6 is hinged to the standard at one end,as'indicated at I, so that it may be swung outwardly to permitpositioning of the shellS between the rolls 5 and 6. Suitablelocking'means Bfjmay be provided at its opposite ends for, holding theroll 6 in its operative position. The rolls 4 and 5 may be hollow andmay be heated by centrally disposed steam pipes 9 and ID. The rolls 4and 5 may be driven by a set of'gears I! towards each other as indicatedin Figure 5. It will be apparent that whenthe roll 5 is driven the shellS will rotate on its cradle and will be moved continuously between therolls 5 and 6 as illustrated in Figure 4.

The container may be formed of spirally wound will be produced. Since athermoplastic resin is used, it will become sufficiently hard as soonend of the film "a has overlapped the other. However, there will be noJoint between the overlappingportions-because of the calenderirmoperation. The film will be continuous as before.

It will be apparent from the above description.

that I have provided a method of applying a protective film or coatingon the interior of a fiber container after the container has been formedin such a manner that there will be no seams in the protective coating.The coating is applied in such a manner that there will be no danger ofit peeling. My method is simple, eifecas the shell of the containercools to the proper extent. Then the shell may be subjected to suitableoperations to apply a bottom thereto. The thickness of thefilm may bevaried by varying the time of calendering and the amount of pressureexerted by rolls 5 and 8.

The thermoplastic resin employed may be in powdered form which is placedtogether with a sufllcient amount of plasticizer into a heated mixerwhich thoroughly mixes the resin and plasticizer in a singlesemi-viscous mass. This mass could then be placed between heatedmalaxating rolls which would thoroughly mix the material and bring it upto the molten plastic consistency suitable for -use on the calenderingrolls. This material may be placed directly on the rolls as shown inFigure '7. The material could then be calendered upon the containershell as a continuous film. Any temperature may be employed in thecalendering operation which will render the film sufliciently plastic tobe calendered. This temperature will depend upon the particular type ofthermoplastic resin employed.

In Figure 8 I illustrate a modification of my 1 invention. In thisinstance thermoplastic resin in the form of a strip I5 is employed. Thisstrip is passed between a heated calendering roll Ba and a pressure roll8a. The continuous strip will be calendered onto the surface of thecontainer as before. The strip I! may be out after one tive andeconomical to perform.

It is to be understood that although I describe my method as beingemployed for coating the interior of a fiber container. it may be usedfor coating the exterior surface thereof if desired.

Having thus described my invention, what I claim is: v

l. The method of applying a protective coating to the surface of a fibercontainer of cylindrical form which comprises rotating the containerabout its axis with. calendaring rolls operating on the interior andexterior surfaces thereof and applying a film of thermoplastic resin toone of said rolls which will transmit it to said surface.

2. The method of applying a protective coating to the surface of a fiberbody of tubular form which comprises rotating the body about its axiswhile simultaneously calendaring a film of ti. ,-rmoplastic resin onsaid surface under. heat and pressure.

8. A method according to claim 2 wherein the film is applied to theinner surface of said body.

4. The method of applying a protective coating to the surface of a fiberbody of tubular form which comprises rotating the body about its axiswhile simultaneously applying a film of thermoplastic resin on saidsurface underheat and pressure.

5. A method according to claim 4 wherein the film is applied to theinner surface of said body.

6. The method of applying a. protective coatingtothe interior surface ofa tubular body having a seam extending longitudinally of said surfacewhich comprises rotating. said body about its axis and simultaneouslycalendering a. continuous film on said inner surface and over said seamby means of heat and pressure.

HANS A. mamass.

